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Dec 9, 2015
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Dec 9, 2015
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Daniel C. Hong; Paul V. Quinn; Stefan Luding
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CanulChay et al. [1] have conducted the segregation experiment of binary granular mixtures in a bed and subjected the bed to vibration. They report that the reverse BrazilNut phenomenon (RBNP) was never observed in their experiments and thus conclude that such does not exist. However, we have clearly demonstrated in [2] by Molecular Dynamics simulations that the reverse BrazilNut problem not only exists, but can be determined from the solidliquid phase boundary by a scaling theory for the...
( 1 reviews )
Source: http://arxiv.org/abs/condmat/0202385v1
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Dec 9, 2015
12/15
Dec 9, 2015
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Paolo Gondolo; Katherine Freese; Douglas Spolyar; Anthony Aguirre; Peter Bodenheimer; Jeremy A. Sellwood; Naoki Yoshida
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The first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the universe. This and the following contribution present the story of Dark Stars. In this first part, we describe the conditions under which dark stars form in the early universe: 1) high dark matter...
( 1 reviews )
Source: http://arxiv.org/abs/0901.4578v1
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Dec 9, 2015
12/15
Dec 9, 2015
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Simon Gruener; Patrick Huber
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Measurements on helium and argon gas flow through an array of parallel, linear channels of 12 nm diameter and 200 micrometer length in a single crystalline silicon membrane reveal a Knudsen diffusion type transport from 10^2 to 10^7 in Knudsen number Kn. The classic scaling prediction for the transport diffusion coefficient on temperature and mass of diffusing species,D_He ~ sqrt(T), is confirmed over a T range from 40 K to 300 K for He and for the ratio of D_He/D_Ar ~ sqrt(m_Ar/m_He)....
( 1 reviews )
Source: http://arxiv.org/abs/0802.1852v1
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Jul 14, 2015
07/15
Jul 14, 2015
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William H. Butler; Claudia K. A. Mewes; Chunsheng Liu; Tianyi Xu
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We present a rational approach to the design of halfmetallic heterostructures which allows the design of an infinite number of halfmetallic heterostructures. The wide range of materials that can be made halfmetallic using our approach makes it possible to engineer materials with tunable characteristic properties, for example low intrinsic magnetic damping, small magnetic moment or perpendicular anisotropy. We demonstrate the proposed design scheme for a series of transition metal...
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Source: http://arxiv.org/abs/1103.3855v1
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Apr 8, 2015
04/15
Apr 8, 2015
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S. AraujoBetancor; B. T. Gaensicke; K. S. Long; K. Beuermann; D. de Martino; E. M. Sion; P. Szkody
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We have obtained HST/STIS data for a total of eleven polars as part of a program aimed to compile a homogeneous database of highquality farultraviolet (FUV) spectra for a large number of cataclysmic variables (CVs). Of the eleven polars, eight were found in a state of low accretion activity (V347Pav, VVPup, V834Cen, BLHyi, MRSer, STLMi, RXJ1554.2+2721 and V895Cen) and three in a state of high activity (CDInd, ANUMa and UWPic). The STIS spectra of the lowstate polars unambiguously reveal the...
favoritefavoritefavoritefavorite ( 1 reviews )
Source: http://arxiv.org/abs/astroph/0412180v1
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Apr 8, 2015
04/15
Apr 8, 2015
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Michael L. Sitko; Lawrence S. Bernstein; Robert J. Glinski
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We have reanalyzed the ultraviolet spectrum of HD 44179, the central star(s) of the Red Rectangle nebula, providing improved estimates of the column density, rotational, and vibrational temperatures of the 4th Positive AX system of CO in absorption. The flux shortward of 2200 A is a complex blend of CO features with no discernible stellar photosphere, making the identification of other molecular species difficult, and the direct derivation of the dust extinction curve impossible. We confirm...
favorite ( 1 reviews )
Source: http://arxiv.org/abs/0802.2085v1
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Mar 15, 2015
03/15
Mar 15, 2015
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Mikhail I. Rabinovich; Mehmet K. Muezzinoglu
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We present a new paradigm in the study of brain mental dynamics on the basis of the stable transient activity neural networks observed in experiments. This new approach is in contrast to traditional system analysis usually adopted in cognitive modeling. Transient dynamics offers a sound formalism of the observed qualities of brain activity, while providing a rigorous set of analysis tools. Transients have two main features: First, they are resistant to noise, and reliable even in the face of...
favoritefavoritefavoritefavorite ( 1 reviews )
Source: http://arxiv.org/abs/0909.1144v1
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Jan 26, 2015
01/15
Jan 26, 2015
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Arkaitz Zubiaga; Damiano Spina; Enrique Amigó; Julio Gonzalo
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This paper explores the realtime summarization of scheduled events such as soccer games from torrential flows of Twitter streams. We propose and evaluate an approach that substantially shrinks the stream of tweets in realtime, and consists of two steps: (i) subevent detection, which determines if something new has occurred, and (ii) tweet selection, which picks a representative tweet to describe each subevent. We compare the summaries generated in three languages for all the soccer games in...
favoritefavoritefavoritefavorite ( 1 reviews )
Source: http://arxiv.org/abs/1204.3731v1
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111
Mar 28, 2014
03/14
Mar 28, 2014
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J. L. F. Barbon
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This is a rendering of a review talk on the state of String Theory, given at the EPS2003 Conference, intended for a wide audience of experimental and theoretical physicists. It emphasizes general ideas rather than technical aspects.
favoritefavoritefavoritefavorite ( 1 reviews )
Source: http://arxiv.org/abs/hepth/0404188v1
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Mar 2, 2014
03/14
Mar 2, 2014
by
Roman Sverdlov
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The first goal of this paper is to show that discreteness, locality, and relativistic covariance can peacefully coexist if the ordinary spacetime (OST) is replaced with phase spacetime (PST) as a geometric background of a Poisson process, where PST is a spacetime generalization of a notion of phase space (this is a 7dimensional version of the 8dimensional structure proposed by Caianiello). Furthermore, Caianiello's idea of finite acceleration is implemented. After this is done, the paper then...
favoritefavoritefavoritefavorite ( 1 reviews )
Source: http://arxiv.org/abs/0910.2498v3
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Nov 7, 2013
11/13
Nov 7, 2013
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Andrei A. Galiautdinov; David R. Finkelstein
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The Dirac equation is not semisimple. We therefore regard it as a contraction of a simpler decontracted theory. The decontracted theory is necessarily purely algebraic and nonlocal. In one simple model the algebra is a Clifford algebra with 6N generators. The quantum imaginary $\hbar i$ is the contraction of a dynamical variable whose backreaction provides the Dirac mass. The simplified Dirac equation is exactly Lorentz invariant but its symmetry group is SO(3,3), a decontraction of the...
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Source: http://arxiv.org/abs/hepth/0106273v2
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P. Laurent; P. Goldoni; A. Goldwurm; F. Lebrun
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The Imager on Board the Integral Satellite (IBIS) is one of the two main telescopes of Integral, the ESA soft gammaray mission to be launched in 2002. The Integral Core Program will be divided into two main parts, the Galactic Centre Deep Exposure program and the Galactic Plane Scan for a total amount of around 6 .6 10^6 seconds each year. In this paper, we will study the visibility of persist ent galactic black holes as observed by IBIS during these two phases of the Core Program. We will...
Source: http://arxiv.org/abs/astroph/0107581v1
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K. Justtanont; L. Decin; F. L. Schoier; M. Maercker; H. Olofsson; V. Bujarrabal; A. P. Marston; D. Teyssier; J. Alcolea; J. Cernicharo; C. Dominik; A. de Koter; G. Melnick; K. Menten; D. Neufeld; P. Planesas; M. Schmidt; R. Szczerba; R. Waters; Th. de Graauw; N. Whyborn; T. Finn; F. Helmich; O. Siebertz; F. Schmulling; V. Ossenkopf; R. Lai
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A set of new, sensitive, and spectrally resolved, submillimeter line observations are used to probe the warm circumstellar gas around the Stype AGB star chi Cyg. The observed lines involve high rotational quantum numbers, which, combined with previously obtained lowerfrequency data, make it possible to study in detail the chemical and physical properties of, essentially, the entire circumstellar envelope of chi Cyg. The data were obtained using the HIFI instrument aboard Herschel, whose high...
Source: http://arxiv.org/abs/1007.1536v1
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F. Fraternali; T. Oosterloo; J. J. Binney; R. Sancisi
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The study of gas outside the plane of disc galaxies is crucial to understanding the circulation of material within a galaxy and between galaxies and the intergalactic environment. We present new HI observations of the edgeon galaxy NGC891, which show an extended halo component lagging behind the disc in rotation. We compare these results for NGC891 with other detections of gaseous haloes. Finally, we present a dynamical model for the formation of extraplanar gas.
Source: http://arxiv.org/abs/astroph/0510734v1
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Chon U. Chan; ClausDieter Ohl
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Here we show a foldingstretching instability in a microfluidic flow focusing device using silicon oil (100cSt) and water. The fluid dynamics video demonstrates an oscillating thread of oil focused by two coflowing streams of water. We show several highspeed sequences of these oscillations with 30,000 frames/s. Once the thread is decelerated in a slower moving pool downstream an instability sets in and waterinoil droplets are formed. We reveal the details of the pinchoff with 500,000...
Source: http://arxiv.org/abs/0910.3159v1
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M. Zingale; A. S. Almgren; J. B. Bell; A. Nonaka; S. E. Woosley
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We present the first threedimensional, fullstar simulations of convection in a white dwarf preceding a Type Ia supernova, specifically the last few hours before ignition. For these longtime calculations we use our low Mach number hydrodynamics code, MAESTRO, which we have further developed to treat spherical stars centered in a threedimensional Cartesian geometry. The main change required is a procedure to map the onedimensional radial base state to and from the Cartesian grid. Our models...
Source: http://arxiv.org/abs/0908.2668v1
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Z. Kaufmann; A. Németh; P. Szépfalusy
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Onedimensional maps exhibiting transient chaos and defined on two preimages of the unit interval [0,1] are investigated. It is shown that such maps have continuously many conditionally invariant measures $\mu_{\sigma}$ scaling at the fixed point at x=0 as $x^{\sigma}$, but smooth elsewhere. Here $\sigma$ should be smaller than a critical value $\sigma_{c}$ that is related to the spectral properties of the FrobeniusPerron operator. The corresponding natural measures are proven to be entirely...
Source: http://arxiv.org/abs/chaodyn/9907003v2
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Tao Zhou; Xiaohua Wu; Gui Lu Long
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The discrimination between two unknown states can be performed by a universal programmable discriminator, where the copies of the two possible states are stored in two program systems respectively and the copies of data, which we want to confirm, are provided in the data system. In the present paper, we propose a grouptheretic approach to the multicopy programmable state discrimination problem. By equivalence of unknown pure states to known mixed states and with the representation theory of...
Source: http://arxiv.org/abs/1112.0931v1
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I contrast the profound differences in the ways in which algebra and analysis are used in physics. In particular I discuss the fascinating phenomenon that theoretical physicists devote almost all their efforts to algebraic problems even though all problems of experimental interest require some methods of analysis.
Source: http://arxiv.org/abs/condmat/0012193v1
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A. Streblyanska; X. Barcons; F. J. Carrera; R. GilMerino
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Broad absorption line quasars (BALQSOs) are key objects for studying the structure and emission/absorption properties of AGN. However, despite their fundamental importance, the properties of BALQSOs are still not well understood. In order to investigate the Xray nature of these sources, as well as the correlations between Xray and restframe UV properties, we compile a large sample of 88 BALQSOs observed by XMMNewton. We performed a full Xray spectral analysis on a sample of 39 sources with...
Source: http://arxiv.org/abs/1002.0723v2
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The last decade has seen an enormous increase of activity in the field of gravitational lensing, mainly driven by improvements of observational capabilities. I will review the basics of gravitational lens theory, just enough to understand the rest of this contribution, and will then concentrate on several of the main applications in cosmology. Cluster lensing, and weak lensing, will constitute the main part of this review.
Source: http://arxiv.org/abs/astroph/9512047v1
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L. Ó Náraigh; P. Spelt; O. Matar; T. Zaki
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We investigate the linear stability of a flat interface that separates a liquid layer from a fullydeveloped turbulent gas flow. In this context, linearstability analysis involves the study of the dynamics of a smallamplitude wave on the interface, and we develop a model that describes waveinduced perturbation turbulent stresses (PTS). We demonstrate the effect of the PTS on the stability properties of the system in two cases: for a laminar thin film, and for deepwater waves. In the first...
Source: http://arxiv.org/abs/0908.1639v1
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K. H. Ahn; A. J. Millis
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A model of localized classical electrons coupled to lattice degrees of freedom and, via the Coulomb interaction, to each other, has been studied to gain insight into the charge and orbital ordering observed in lightly doped manganese perovskites. Expressions are obtained for the minimum energy and ionic displacements caused by given hole and electron orbital configurations. The expressions are analyzed for several hole configurations, including that experimentally observed by Yamada et al. in...
Source: http://arxiv.org/abs/condmat/9802184v2
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D0 Collaboration; V. Abazov
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We present evidence for diffractive exclusive dijet production with an invariant dijet mass greater than 100 GeV in data collected with the D0 experiment at the Fermilab Tevatron Collider. A discriminant based on calorimeter information is used to measure a significant number of events with little energy (typically less than 10 GeV) outside the dijet system, consistent with the diffractive exclusive dijet production topology. The probability for these events to be explained by other dijet...
Source: http://arxiv.org/abs/1009.2444v1
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Zheng Wang; Y. D. Chong; John D. Joannopoulos; Marin Soljacic
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We point out that electromagnetic oneway edge modes analogous to quantum Hall edge states, originally predicted by Raghu and Haldane in 2D gyroelectric photonic crystals possessing Dirac pointderived bandgaps, can appear in more general settings. In particular, we show that the TM modes in a gyromagnetic photonic crystal can be formally mapped to electronic wavefunctions in a periodic electromagnetic field, so that the only requirement for the existence of oneway edge modes is that the Chern...
Source: http://arxiv.org/abs/0712.1776v2
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R. Zhang; B. I. Shklovskii
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In a recent experiment, a single DNA double helix is stretched and relaxed in the presence of spermidine, a short positive polyelectrolyte, and the pulling force is measured as a function of DNA extension. In a certain range of spermidine concentration, a force plateau appears whose value shows maximum as a function of spermidine concentration. We present a quantitative theory of this plateau force based on the theory of reentrant condensation and derive almost parabolic behavior of the plateau...
Source: http://arxiv.org/abs/condmat/0310321v3
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J. M. Alarcón; J. Martín Camalich; J. A. Oller; L. AlvarezRuso
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We have analyzed pionnucleon scattering using the manifestly relativistic covariant frameworks of Infrared Regularization (IR) and ExtendedOnMassShell (EOMS) up to O(q^3) in the chiral expansion, where q is a generic small momentum. We describe the lowenergy phase shifts with a similar quality as previously achieved with Heavy Baryon Chiral Perturbation Theory, being the EOMS description better than the IR one. The GoldbergerTreiman discrepancy is extracted from data of partial wave...
Source: http://arxiv.org/abs/1107.3989v1
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R. C. Kapoor; C. S. Shukre
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We present a new method for investigating emission altitudes of radio pulsar core and conal components by attributing them different altitudes and by providing a framework to understand the resulting longitude offsets between them which are frequently observed. By investigating the contributions to these offsets due to aberration and the magnetic field line sweepback, we show that they are always dominated by aberration for all emission altitudes and inclination angles. This directly allows the...
Source: http://arxiv.org/abs/astroph/0205429v1
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C. N. Hind; A. O. Gogolin
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We study a simple model of the twochannel Kondo effect in a distorted crystal. This model is then used to investigate the interplay of the Kondo and JahnTeller effects, and also the Kondo effect in an impure crystal. We find that the JahnTeller interaction modifies the characteristic energy scale of the system below which nonFermiliquid properties of the model become apparent. The modified energy scale tends to zero as the limit of a purely static JahnTeller effect is approached. We find...
Source: http://arxiv.org/abs/condmat/9806218v1
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Maria Valentina Carlucci
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We discuss the theoretical and experimental details of two of the main results obtained by LHCb with the 2011 data, namely the measurement of the mixinginduced CPviolation in the decay B_s > J/psi phi and the upper limits on the decays B_(s) > mu+ mu. Then we describe the possible strategies to obtain new constraints on two different New Physics models in the light of these results.
Source: http://arxiv.org/abs/1209.5230v1
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A rapidity gap trigger for the ALICE detector at the Large Hadron Collider LHC is presented and a few selected physics observables are discussed. First, some properties of double pomeron events are outlined. Second, signatures of the odderon in diffractive J/Psi production is discussed. Third, possible evidence of gluon saturation in the cross section of diffractive heavy quark photoproduction is investigated.
Source: http://arxiv.org/abs/0801.4890v1
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R. A. Dias; M. Rapini; P. Z. Coura; B. V. Costa
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We use Monte Carlo and molecular dynamics simulation to study a magnetic tipsample interaction. Our interest is to understand the mechanism of heat dissipation when the forces involved in the system are magnetic in essence. We consider a magnetic crystalline substrate composed of several layers interacting magnetically with a tip. The set is put thermally in equilibrium at temperature T by using a numerical Monte Carlo technique. By using that configuration we study its dynamical evolution by...
Source: http://arxiv.org/abs/physics/0604092v1
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Megan Donahue; G. Mark Voit; Christopher P. O'Dea; Stefi A. Baum; William B. Sparks
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Radio lobes inflated by active galactic nuclei at the centers of clusters are a promising candidate for halting condensation in clusters with short central cooling times because they are common in such clusters. In order to test the AGNheating hypothesis, we obtained Chandra observations of two clusters with short central cooling times yet no evidence for AGN activity: Abell 1650 and Abell 2244. The cores of these clusters indeed appear systematically different from cores with more prominent...
Source: http://arxiv.org/abs/astroph/0508587v1
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Stephan Baier; Sawian Jaidee; Shaun Stevens; Thomas Ward
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We exhibit continua on two different growth scales in the dynamical Mertens' theorem for ergodic automorphisms of onedimensional solenoids.
Source: http://arxiv.org/abs/1201.4503v1
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H. Christian Estler; Carlo A. Furia; Martin Nordio; Marco Piccioni; Bertrand Meyer
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Contracts are a form of lightweight formal specification embedded in the program text. Being executable parts of the code, they encourage programmers to devote proper attention to specifications, and help maintain consistency between specification and implementation as the program evolves. The present study investigates how contracts are used in the practice of software development. Based on an extensive empirical analysis of 21 contractequipped Eiffel, C#, and Java projects totaling more than...
Source: http://arxiv.org/abs/1211.4775v5
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This is a study of holomorphic matrix models, the matrix models which underlie the conjecture of Dijkgraaf and Vafa. I first give a systematic description of the holomorphic onematrix model. After discussing its convergence sectors, I show that certain puzzles related to its perturbative expansion admit a simple resolution in the holomorphic setup. Constructing a `complex' microcanonical ensemble, I check that the basic requirements of the conjecture (in particular, the special geometry...
Source: http://arxiv.org/abs/hepth/0303008v3
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Adrian Signer; Dominik Stockinger
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We discuss how to apply regularization by dimensional reduction for computing hadronic cross sections at nexttoleading order. We analyze the infrared singularity structure, demonstrate that there are no problems with factorization, and show how to use dimensional reduction in conjunction with standard parton distribution functions. We clarify that different versions of dimensional reduction with different infrared and factorization behaviour have been used in the literature. Finally, we give...
Source: http://arxiv.org/abs/0807.4424v1
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We make a preliminary algebraic study of supersymmetric deformations of N=1 YangMills theory in dimension ten with an arbitrary gauge group. This is done in a context of Lie algebra deformation theory. The tangent space to the space of deformation is computed.
Source: http://arxiv.org/abs/hepth/0601010v1
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Itaï Ben Yaacov; Alexander Berenstein; Stefano Ferri
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It is wellknown that a topological group can be represented as a group of isometries of a reflexive Banach space if and only if its topology is induced by weakly almost periodic functions (see \cite{Shtern:CompactSemitopologicalSemigroups}, \cite{Megrelishvili:OperatorTopologies} and \cite{Megrelishvili:TopologicalTransformations}). We show that for a metrisable group this is equivalent to the property that its metric is uniformly equivalent to a stable metric in the sense of Krivine and...
Source: http://arxiv.org/abs/0901.1003v2
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We obtain the energy distribution in the KerrNewman metric with the help of BergmannThomson energymomentum complex. We find that the energymomentum definitions prescribed by Einstein, LandauLifshitz, Papapetrou, Weinberg, and BergmannThomson give the same and acceptable result and also support the {\em Cooperstock Hypothesis} for energy localization in general relativity. The repulsive effect due to the electric charge and rotation parameters of the metric is also reflected from the...
Source: http://arxiv.org/abs/hepth/0308077v1
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R. Esposito; Y. Guo; R. Marra
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There are not many kinetic models where it is possible to prove bifurcation phenomena for any value of the Knudsen number. Here we consider a binary mixture over a line with collisions and long range repulsive interaction between different species. It undergoes a segregation phase transition at sufficiently low temperature. The spatially homogeneous Maxwellian equilibrium corresponding to the mixed phase, minimizing the free energy at high temperature, changes into a maximizer when the...
Source: http://arxiv.org/abs/0904.0791v1
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We estimate the charged lepton electric dipole moments and the branching ratios of radiative lepton flavor violating decays in the framework of the two Higgs doublet model with the inclusion two extra dimensions. Here, we consider that the new Higgs doublet is accessible to one of the extra dimensions with a Gaussian profile and the fermions are accessible to the other extra dimension with uniform zero mode profile. We observe that the numerical values of the physical quantities studied enhance...
Source: http://arxiv.org/abs/hepph/0606165v2
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Adam J. Burgasser; J. Davy Kirkpatrick
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We report the discovery of LEHPM 259 as the coolest extreme M subdwarf (esdM) found to date. Optical and near infrared spectroscopy demonstrate that this source is of later spectral type than the esdM7 APMPM 05592903, with the presence of strong alkali lines (including Rb I), VO absorption at 7400 A and H2O absorption at 1.4 microns. Current optical classification schemes yield a spectral type of esdM8, making LEHPM 259 one of only two ultracool esdMs known. The substantial space velocity of...
Source: http://arxiv.org/abs/astroph/0603382v1
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Bakhadyr Khoussainov; Andre Nies; Sasha Rubin; Frank Stephan
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We study the existence of automatic presentations for various algebraic structures. An automatic presentation of a structure is a description of the universe of the structure by a regular set of words, and the interpretation of the relations by synchronised automata. Our first topic concerns characterising classes of automatic structures. We supply a characterisation of the automatic Boolean algebras, and it is proven that the free Abelian group of infinite rank, as well as certain Fraisse...
Source: http://arxiv.org/abs/cs/0703064v2
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Yuhai Tu; J. Tersoff; G. Grinstein; David Vanderbilt
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We use a Monte Carlo bondswitching method to study systematically the thermodynamic properties of a "continuous random network" model, the canonical model for such amorphous systems as aSi and aSiO$_2$. Simulations show firstorder "melting" into an amorphous state, and clear evidence for a glass transition in the supercooled liquid. The randomnetwork model is also extended to study heterogeneous structures, such as the interface between amorphous and crystalline Si.
Source: http://arxiv.org/abs/condmat/9807211v1